By Bill Cavins
Are you wasting good, treated water while you wait for your shower to get hot? Do you have to run water in the kitchen to get hot water to the dishwasher? Are you committed to water conservation? Did you know that every home wastes thousands of gallons of water a year waiting for it to get hot?
Demand hot water circulation systems are not new. They have been around for a long time, but with our current water shortage, they could be a great contributor to water conservation.
The concept is this: At the push of a button, water is pumped from the hot water line back into the cold water line at the water fixture furthest from the water heater, usually a bathroom. A temperature-sensor detects an increase in the water temperature as hot water arrives and shuts the pump off. Meaning, while you are getting ready for your shower, no water is wasted. The pump runs for less than a minute, and hot water is immediately available wherever the pump is installed, usually at the bathroom sink.
Whether or not hot water is then available at other locations in your house depends on the plumbing layout. Ideally if there is only one main hot water line with small branches to the kitchen, bathrooms and laundry, installing the pump at the end of the line should provide hot water within seconds anywhere in the house. (Remote buttons can be placed at other locations.) If the farthest point is at the end of one branch — for example, the master bath, with the kitchen at the end of another branch — this will affect the time it takes for hot water to reach the kitchen. A second pump would be required.
For tankless water heaters, the pump must have a high enough flow rate to activate the water heater, 10 gallons/minute is recommended. For pipe runs of more than 100 feet, a bigger pump is required, such as 20 gallons/minute.
These demand systems are simple to install — hardware kits are available. However, they do require an electrical outlet. In the case of a bathroom sink, on outlet can usually be added by extending wiring from an existing outlet by the sink. This is the only part of the installation that requires trade skills, as well as a permit.
The “button” is actually a doorbell button and is low voltage. An optional remote receiver hooks right up to the unit so it can be turned on from anywhere in the house with a remote transmitter button.
There are a variety of choices in demand hot water systems, including companies such as ACT, Watts and Grundfos. Costs are in the $200 to $300 range.
— Bill Cavins is from Ganesh Works in Davis.